Interference-free sound reproducing device



July 26, 1932. o. wENDERoTH INTERFERENCE FREE SOUND 'REPRODUCING DEVICEFiledv July 50, 1929 2 Sheets-Sheet l R O T N E V m Oscar WenderoHfl IHis "pw l RNEY July 26, 1932. o. wEr-1|:n-:R 3THi INTERFERENCE FREESOUND REPRODUCING DEVICE Filed July 50. 1929 2 Sheets-Sheet 2 lNvENToROscar Wenderorh Y ATTORNEY Patented July 26, v1932 UNiTEnV *s'iui'rssPATN OSCAR WENDEROTH, OF NEW YORK, N. lY.

INTERFERENCE-FREE SOUND REPRODUCING Application filed July 30, 1929.

My invention relates to improvements in phonographs, radio speakers, andother sound reproducing devices.

An object of the invention is to conserve the purity and volume of thetones Which originate in the reproducing system of a phonograph and thelike and of the sound producing parts of a radio speaker, announcer andthe like. Y Y* f In present and prior phonographs, radio speakers,announcers and other reproducers, serious acoustical defects `andlimitations have been noted. These defects and limitations I designateherein as interferences, and by this ter-1n I include the defects andlimitations recognized in phonographic reproduction as strident tones,non-unifori ity of quality and volume of different registers Within therange of reproduction, varying individually in different phonographs andmakes of phonographs, giving rise to socalled peaks, dead spots, andthe-like. By the term interference I also include c acousticaldistortions which arise from varying causes, as Will appear, and whichdeprive or suppress the reproduction of overtones asy Well as impressdissonant and/or discordant tones and/or noises.

I have discovered that such interferences arise from the followingcauses, the order of enumeration of these causes being Without referenceto their degree or relative importance; firstly, the vibrationsoriginating in the reproducing system of a phonograph and the soundproducing or emitting parts of a radio speakerV and the like in turn setup vibrations in the material forming the reproducing system, in Wholeor in substantial A part thereof; secondly, the vibrations originatingin the reproducing system or the sound producing parts by communicationWith the'air Within the turntable Well, in the instance of a phonograph,set up vibrations of the Wall materials, thereby superimposing suchvibrations upon the original vibrations;

Serial No. 382,163.

tions set up in thel tone Vhorn giverise in turn to vibrations of theWalls and other parts of the chamber or chambers enclosing or adj acentthe tone horn; sounds and/or noises extraneous'ofthe phonograph, radiospeaker, and the like are permitted to enter the reproducing or soundproducing system or parts.

Aside from the interferences arising from extraneous sounds or noisesand that due to defective structural relation of the tone horn, theabove stated and other interfering'vibrations are engendered in partswhich fare accessory to the reproducing and amplifying system proper.vand are of or included-in the construction of the cabinet orotherenclosure for the reproduction and' amplifying system proper. p

Stated broadly, my invention overcomes the above stated and otherinterferences by precluding or at least minimizing vibrations of thecabinet and other accessory parts'by forming of or having the innerWalls provided With sound absorbing and/or sound insulating material,thereby suppressing vthe vibrations of the materials ofthe reproducingsystem or soundprodu'cing parts, by constructing and mounting the tonehorn to have its amplifying portion acoustically'free of the Walls andother accessory parts, and by y positively excluding from thereproducing system or sound producing parts all eXtranev ous sounds andnoises. f Y Further features and objects ofthe invention Will be morefully understood fromthe following detailed description and theaccompanying drawings, in Which Fig. 'l is a vertical sectionalelevation of a phonograph embodying preferred forms of my invention,applied to a phonograph;

Fig. 2 is a top plan-view of the turntabley "i Well of the phonograph ofFig. l;

Fig. 3 is a sectional elevation on line 3 3 of Fig. 1*; and f Fig. 4 isa sectional elevation on line {lr-4 of Fig. 1. f

As above indicated', my invention is applicable to all forms of soundreproducing'. devices and accordingly my invention is not limited to anyparticular adaptation to phonographs generally nor tothe particular lOOstructure indicated in the drawings for carrying out my invention.

As illustrated in the drawings, the cabinet lO-of the phonograph isshown of conventional type and comprises generally an upper section 11,usually called the turntable well, and a lower section 12, usuallycalled the tone horn chamber. The turntable well, as usual,

lis illustrated as provided with a cover 13 which is hinged at its oneside, as indicated at 14. As will appear, the rigidity of the body, i.e. walls of the phono-graph orfother sound reproducing device isattained bythe use of suitable material, such as wood, similar to priorand present day practice, but, as appears more fully hereinafter, rigidmaterial such as metalmay be employed, in combination with suitablesound absorbing and/or sound insulatingmaterials. Thus, as isillustrated particularly in Figs. 1 and 2, and as applied to aconventional type of phonograph cabinet, the selected rigid material isshown as the outer material of the cabinet walls and the material forattaining the objects of my invention applied as inner material, or asfaCingS, or linings, upon or of the inner faces of the rigid material.

As one material for obtaining certain of the objects of my invention, Iillustrate the layer 15 of felt, of sufficient thickness to serve as asound absorbing medium. In the drawings, I have further shown theconjoint use of suitable sound insulating material such as corrugatedboard 16 of paper stock, or the like, or other sound insulating materialof cellular or dead air spaces, or of non-cellular formation, as will beunderstood by the art. With the conjoint use of such sound absorbingVand sound insulating materials, the combined thickness of the. same maybe reduced, ascompared with the use of a single materialV serving as thesound absorbing and/or sound insulating medium.

Such sound proofing and sound insulating construction is illustrated inthe drawings las applied to or upon all inner faces of the turntableWell, including the four vertical walls, in which instances the wood orother rigid material of these walls are preferably recessed to receivesuch medium and also to provide a rim or beading 17 extending as ytheeffective upper edge of the .turntable well, the rigid material of thecover 12 being ,also recessed at its inner faces to receive the soundproofing materiall and/or the sound insulating material 16,V thedimensions of length and width of the cover recess extending `beyond.the beading 17 whereby the upper edges of the beading 17 engage thesound proofing and/orvsound insulating material, when the cover'13 is`in its closed position.

Such structural relationship precludes the entry into the turntable wellof sounds yor noises vextraneous of the phonograph reproducing system,as referred to else-where herein, as well as attaining the above statedobjects of sound proofing and sound insulating.

Such construction also enables the thus closed interior of the turntablewell to adjust itself to varying atmospheric conditions, as will be nowapparent.

Such sound proofing and insulating materials are illustrated similarlyapplied to the inner walls of the tone horn chamber 12, inV

this instance, Fig. 1 indicating the sound proofing material 15 of feltand the sound insulating material 16 of cellular material. The door ordoors 18 of the tone horn chamber, hinged to swing in a horizontalplane, or otherwise suitably adjustably supported from the frontvertical wall 19 of the cabinet may also be provided with sound proofingand/or sound insulating materials. Y

Any suitable grill for concealingthe opening of the tone horn may beemployed.

My invention is more fully realized by the use of the sound proofingand/or sound insulating materials for the partition 20, usuallyincluding a central removable board or panel 21 between the turntableWell 1.1 and the tone horn chamber 12, the sound proofing material beingsimilarly indicated rat 15 and the sound insulating material 16,

such sound proofing and sound insulating material is preferably alsocontinued over the edge faces of the removable board 21 adjacent theedge faces of the body or the partition 20, as is indicated at 22.

As one manner of effectually suppressing vibrations normally imposedupon the metal or other material of the sound boX, tone arm and likeparts of the reproducing system of a phonograph or the like, I applysuitable material such as tape 23, wholly or partially v about the tonearm and the like, by enwrapping the same under pressure, shrinking orlike procedure. tional type of tone arm, the same is swiveled at itslower end 24 to a collar 25, the swiveling being about a pivotal arm 26,provided with a lower, horizontally extending flange 27, and carrying atits upper end a pivot or swivel pin 28, received vwithin a recessed boss29 or equivalent. Such collar 25 is usually locked in position by thelock nut 30 applied on the lower face of the partition 20. Pursuant tomy invention, the sound proofing and/or sound insulating material ormaterials, 15, 16 are shown interposed between such fiange 23 andthepartition 20, and between the lock nut 30, and at other clearancesbetween such rigid material parts. Similarly, in the further attainmentof my invention, substantial preclusion of interference is had byapplying under-pressure tape or the like, aboutthe circular edge, theopposite faces and other portions of the sound boX 31.

In like'manner, the turntable 32 of ymetal orlike rigid material isprecluded from act- In the illustrated convening as a diaphragm andcausing the record disk to similarly act as a diaphragm, or otherwisecontributing interfering vibrations by applying sound proofing material15 and/or sound insulating material 16 upon the upper face of theturntable, and in the instance of the use of felt alone as suchmaterial, the thickness of the felt is substantial and sufficient forattaining the above stated purposes; such sound absorbing and/orprooiing material is also applied upon under surfaces and the edge ofthe turntable.

When the turntable or equivalent is driven by clockwork mechanism,usually enclosed within a housing 33 or separate chamber which may be ofsteel or the like, its walls are precluded from acting as diaphragms orotherwise transmitting interference and the vibrations arising from themovement of the motor parts suppressed, by means of sound proof material15 and/or sound insulating material 16, applied similarly to the-same,including the contiguous faces between the upper edges 34 of the housingor chamber 33 and the bottom face of the partition 20, and/or of thepartition board 21, as is indicated in this instance at 35.

The tone arm, turntable, and other parts of the reproducing system maybe Vformed wholly or partly of material per se possessing relatively lowinherent vibration, in which arrangement the sound absorbing and/orsound insulating material may be reduced to minimum thickness oromitted.

One type of tone horn is indicated at 36, which may be of the regulationor other approved construction; in all instances of which my inventionis applicable. As indicated above, the tone horn is per se constructedand arranged to have free vamplifying action, and as one manner ofcarrying out my invention, I have shown its upper or neck portion 37 ofthe tone horn secured to the lower end 38 of the collar 25 as anacoustical nodal point, namely, by the use of a combined bracket andclamp; the bracket portion of which, indicated at 39, is secured byscrews 40 or the like to any suitable rigid support, such as the rearwall of the tone horn chamber 12; such bracket 39 is shown comprisingthe oppositely disposed clamping arms 41, 41, the free ends of which areadjustably clamped by means of the screw 42 and nut 43; the neck 37 ofthe tone horn 36 is sound proofed and/or sound insulated from the collar25 by the material indicated at 44, see Figs. 1 and 4, similarly asabove stated.

The body of the tone horn 36 is wrapped under pressure with vibrationretarding material, and/or covered with sound absorbing and/or soundinsulating material or materials, as indicated at 45.

Where any support or supports supplemental to the above stated nodalsupport at the inner end37 ofthe tone horn36may: be required ordesired,particularly for retaining the tone horn in position duringshipment and/,or other removal from one' location to another location,such supplemental support may be hadby interposing sound proofing and/or sound insulating material between the rigid portion or material ofsuch ysupport andl its engagement with the material per se of thev tonehorn .36., asby the 'use ofsupplemental supporting blocks or the likeindicatedl Aat 46, which may rest upon 'the sound'prooiing and/or soundinsulating material 15, 16, at the bottom' of the tone horn chamber 12,such supporting elementsv 46 further having on its engaging, i'. e.,upperAV face 47 sound proofing and/ or soundinsulating materialindicated. at 48, to sound proof and/or sound insulate such face orfaces 47 from the material of the tonel horn 36 proper.

In further attainment of my invention, all parts of metal andotherrelatively rigid and of inherently vibrator-'y character whetherrequired or employed in the cabinetconstruction or otherwise accessoryor incidental to the 'reproducing system proper land the tone hornproper, are precluded from Vibrating or otherwisecontributinginterference and or restricting the range, the quality or timbre oraffecting any overtones, and/or other forms of interference, by havingtheirrsound exposed surfaces covered with sound absorbing and/or soundinsulating materials, similarly as above. As instances of such feature,I illustrate the connection and support of the removable panel 21relative to the partition 20, 'comprising' the bracket 50 and removablescrewsj51, provided with sound absorbing and/or sound insulatingmaterial as is indicated at 52, 52, see Figs. 1 and 2, .interposedbetween rigid materials wherever employed; similarly the stylus `orneedles are precluded from contributing interference, by

locating the receptacle for the fresh and used needles at a locationacoustically extraneous of the yreproducing and sound amplifying systemproper. Forexample, such receptacle 53 may be located within an outerportion of the cabinet Wall, as indicatedin Fig. 1, conveniently at thefront of the cabinet; such receptacle 53, see Fig.'3, may compriseseveral sub-compartments 54 for the fresh needles and a centralcompartment 55 for used needles. It should be further noted that soundabsorbing and sound insulating material 15, 16, see Figsfl and 3, areinterposed between the reproducing and sound amplifying system properandthe interior of the i *.withinzcabinets, casings, housings or thelike, including portable phonographs.

Whereas, I. havefdescribed my invention by reference to speci-lic formsthereof,A it will fbe understood that many'changes and modi-V icationsmay be made Without departing from: the spirit of the invention.

I-claim :w- Y

l. In a sound producing device embodying -an actuated sound producingelement and accessory parts for the support of Athe same7 :and a housingfor said actuated element and said accessory parts,` said housing havingwalls of material normally set in vibration upon actuation of said soundproducing elejment, and sound absorbing and sound insulating. materialdisposed on faces of said 'housing directed toward said actuated soundproducing element for precluding vibration rby said accessory parts ininterference of the vibrations produced by said actuated element.

u2. In a sound producing device embodying lan actuated sound producingelement and accessory parts for the support of the same, and a housingfor said actuated part and said accessory parts, said housingbeing-,self-en- Y closed and formed of material normally set invibration upon actuation of said sound producing element, and soundabsorbing and sound insulating material disposed on substantially allthe inner faces of said housing directed toward said accessory parts forprecluding vibration by said accessory parts and said housing ininterference of the vibrations produced by said actuated element.

In testimony whereof I have signed this specification this 21st day ofJanuary, 1929. Y

OSCAR VVENDEROTH.

